The present invention relates to generally a remote-control gearshift mechanism for a vehicular transmission and more particularly a steering column type remote-control gearshift mechanism for a four-or five-speeds automotive transmission.
As is well known, in the conventional remote-control gearshift mechanism of the type described, a driver shifts a gearshift level to cause the axial movement and rotation of a control shaft extended in parallel with a steering column, and the axial and rotary movements of the control shaft are transmitted through a linkage to a transmission so that a desired gearshift may be made. In a four- or five-speeds transmission, in general, the control shaft is so arranged as to shift between three positions in the axial direction and is so biased by springs at both ends of the control shaft in opposite directions that the control shaft may be automatically returned to the intermediate or neutral position. However, only one of the two springs is provided with means for limiting the expansion range of this spring in such a way that the force of the spring may not be further exerted to the control shaft once the latter has been returned to its neutral position. Whereas the expansion range of the other bias spring is restricted by the force of one spring so that the control shaft may be prevented from moving past its neutral position. Accordingly the force of one spring must be stronger than that of the other spring and as a result the gear shifting forces required for causing the control shaft to shift upward or downward from its neutral position are different in magnitude and consequently a driver feels unbalanced gearshift actions. In order to ensure light gearshift-action feeling, the weaker the springs, the better, but the force of one spring cannot be reduced beyond a certain magnitude because the force of the other spring must be so excessively reduced due to the reason described above that it cannot bring the control shaft back to its neutral position.